A wind power generation system generates power by utilizing wind power energy being renewable energy. In the wind power generation system, when a wind speed and a wind direction suddenly fluctuate, a speed triangle around a windmill blade greatly deviates from a rating point, so that a separated flow sometimes occurs in a wide range. When the wind speed and the wind direction suddenly fluctuate, it is not easy to sufficiently respond to the fluctuations by adjustment of a yaw angle or a pitch angle. As a result of this, in the wind power generation system, there may be cases where it is difficult to keep a power generation output to a stable one, and it is not easy to increase an efficiency. In particular, in a region having a mountain climate such as in Japan, a wind speed and a wind direction change greatly, so that a power generation output cannot be kept stably, and thus it is not easy to increase an efficiency. Other than the above, when a wind power generation system is installed at a place near a private house and the like, a generation of noise sometimes becomes a problem.
As a measure for the above, it has been proposed to use an airflow generation device to generate an airflow at a surface of a windmill blade. The airflow generation device has a main body to which a pair of electrodes are provided via a dielectric, and the main body is disposed on a surface of a windmill blade. Further, the airflow generation device generates an airflow when a voltage application unit (discharge power supply) applies a voltage between the pair of electrodes to generate a plasma. For example, a pulse modulation frequency is set in accordance with a rotation speed of a windmill blade detected by a rotation speed detecting unit (rotation speed sensor), and a high-frequency voltage which is pulse-modulated by the set pulse modulation frequency is applied between the pair of electrodes. By generating the airflow using the airflow generation device as described above, it is possible to control a flow of a fluid at the surface of the windmill blade to suppress an occurrence of separated flow. As a result of this, a lift of the windmill blade increases, and it is possible to realize not only a stabilization of power generation but also an improvement in power generation efficiency. Further, it is possible to suppress a generation of noise.
In a wind power generation system, an application of voltage is performed on a rotary body from a stationary body via a slip ring, for example.
In a wind power generation system, a voltage application unit (discharge power supply) is mounted on a rotary body such as a windmill blade so that a high voltage is not supplied to a main body of an airflow generation device via a slip ring, by taking efficiency and safety into consideration. In this case, data of rotation speed detected by a rotation speed detecting unit (rotation speed sensor) disposed on a stationary body such as a nacelle is transmitted to the voltage application unit disposed on the rotary body via the slip ring. For this reason, a malfunction sometimes occurs due to a noise caused by the slip ring. Further, since a number of poles of the slip ring increases, there is a case where it becomes difficult to dispose the airflow generation device in an existing wind power generation system, in particular.
Therefore, a problem to be solved by the present invention is to provide an airflow generation device, and a wind power generation system capable of suppressing an increase in a number of poles of a slip ring, and effectively preventing a malfunction from occurring due to a generation of noise caused by the slip ring.